/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: BoolStack.java,v 1.1.4.1 2005/09/08 11:03:08 suresh_emailid Exp $
 */
package com.sun.org.apache.xml.internal.serializer.utils;

/**
 * Simple stack for boolean values.
 *
 * This class is a copy of the one in com.sun.org.apache.xml.internal.utils.
 * It exists to cut the serializers dependancy on that package.
 * A minor changes from that package are:
 * doesn't implement Clonable
 *
 * This class is not a public API, it is only public because it is
 * used in com.sun.org.apache.xml.internal.serializer.
 *
 * @xsl.usage internal
 */
public final class BoolStack {

    /** Array of boolean values          */
    private boolean m_values[];

    /** Array size allocated           */
    private int m_allocatedSize;

    /** Index into the array of booleans          */
    private int m_index;

    /**
     * Default constructor.  Note that the default
     * block size is very small, for small lists.
     */
    public BoolStack() {
        this(32);
    }

    /**
     * Construct a IntVector, using the given block size.
     *
     * @param size array size to allocate
     */
    public BoolStack(int size) {

        m_allocatedSize = size;
        m_values = new boolean[size];
        m_index = -1;
    }

    /**
     * Get the length of the list.
     *
     * @return Current length of the list
     */
    public final int size() {
        return m_index + 1;
    }

    /**
     * Clears the stack.
     *
     */
    public final void clear() {
        m_index = -1;
    }

    /**
     * Pushes an item onto the top of this stack.
     *
     *
     * @param val the boolean to be pushed onto this stack.
     * @return  the <code>item</code> argument.
     */
    public final boolean push(boolean val) {

        if (m_index == m_allocatedSize - 1)
            grow();

        return (m_values[++m_index] = val);
    }

    /**
     * Removes the object at the top of this stack and returns that
     * object as the value of this function.
     *
     * @return     The object at the top of this stack.
     * @throws  EmptyStackException  if this stack is empty.
     */
    public final boolean pop() {
        return m_values[m_index--];
    }

    /**
     * Removes the object at the top of this stack and returns the
     * next object at the top as the value of this function.
     *
     *
     * @return Next object to the top or false if none there
     */
    public final boolean popAndTop() {

        m_index--;

        return (m_index >= 0) ? m_values[m_index] : false;
    }

    /**
     * Set the item at the top of this stack
     *
     *
     * @param b Object to set at the top of this stack
     */
    public final void setTop(boolean b) {
        m_values[m_index] = b;
    }

    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.
     *
     * @return     the object at the top of this stack.
     * @throws  EmptyStackException  if this stack is empty.
     */
    public final boolean peek() {
        return m_values[m_index];
    }

    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.  If the stack is empty, it returns false.
     *
     * @return     the object at the top of this stack.
     */
    public final boolean peekOrFalse() {
        return (m_index > -1) ? m_values[m_index] : false;
    }

    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.  If the stack is empty, it returns true.
     *
     * @return     the object at the top of this stack.
     */
    public final boolean peekOrTrue() {
        return (m_index > -1) ? m_values[m_index] : true;
    }

    /**
     * Tests if this stack is empty.
     *
     * @return  <code>true</code> if this stack is empty;
     *          <code>false</code> otherwise.
     */
    public boolean isEmpty() {
        return (m_index == -1);
    }

    /**
     * Grows the size of the stack
     *
     */
    private void grow() {

        m_allocatedSize *= 2;

        boolean newVector[] = new boolean[m_allocatedSize];

        System.arraycopy(m_values, 0, newVector, 0, m_index + 1);

        m_values = newVector;
    }
}
